In the field of medicine, the term “therapeutic apheresis” refers to techniques for treating diseases using the patient's blood. Current medical practice extracts whole blood from the patient and, as a first stage, separates the plasma from the blood ex-vivo by centrifugal or membrane separation, and in a second stage treats the separated plasma by various techniques. The treated plasma and blood are recombined ex-vivo and returned to the patient. In the simplest procedure the separated plasma including the pathogenic macromolecules is discarded and substitution fluids such as fresh frozen plasma and albumen solution are re-infused to the patient.
In all of the aforesaid and currently practiced therapeutic apheresis procedures, whole blood must be removed from the body and processed in two ex-vivo stages. However, removal and treatment of whole blood has major disadvantages. Whole blood removal results in the necessity to heparinize or anticoagulate the patient to minimize clotting in the ex-vivo circuit and apparatus. Such treatment is counter-indicated in most surgical patients and deleterious to others due to consequential damage to blood components and the removal of vital blood components unrelated to the therapy. Removing and treating whole blood ex-vivo dictates that the procedure be a “batch” or intermittent process with attendant loss of efficiency and confinement of the patient to a clinical setting where support systems and machinery are available. Removal of whole blood also exposes the patient to contamination by viral and/or bacterial infection from nosocomial sources, and removal of erythrocytes, platelets and other large cellular blood components exposes them to risk of damage due to mechanical and chemical exposure to non-biocompatible surfaces of ex-vivo apparatus.